Encyclopædia Britannica, Ninth Edition/Anchor

by Thomas Morley

ANCHOR, in Navigation, from the Greek ἄγκυρα, which Vossius thinks is from ὄγκη, a crook or hook, an instrument of iron or other heavy material used for holding ships in any situation in which they may be required to lie, and preventing them from drifting by the winds or tides, by the currents of rivers, or any other cause. This is done by the anchor, after it is let down from the ship by means of the cable, fixing itself into the ground, and there holding the vessel fast. The anchor is thus obviously an implement of the first importance in navigation, and one on which too much attention cannot be bestowed in its manufacture and proper construction, seeing that on it depends the safety of the vessel in storms. The invention of so necessary an instrument is to be referred, as may be supposed, to the remotest antiquity. The most ancient anchors consisted merely of large stones, baskets full of stones, sacks filled with sand, or logs of wood loaded with lead. Of this kind were the anchors of the ancient Greeks, which, according to Apollonius Rhodius and Stephen of Byzantium, were formed of stone; and Athenæus states that they were sometimes made of wood. These sorts of anchors retained the vessel merely by their inertia, and by the friction along the bottom. Iron was afterwards introduced for the construction of anchors, and also the grand improvement of forming them with teeth or flukes to fasten themselves into the bottom; whence the words ὀδόντες and dentes are frequently taken for anchors in the Greek and Latin poets. The invention of the teeth is ascribed by Pliny to the Tuscans; but Pausanias gives the merit to Midas, king of Phrygia. Originally there was only one fluke or tooth, whence anchors were called ἑτερόστομοι; but shortly afterwards the second was added, according to Pliny, by Eupalamus, or, according to Strabo, by Anacharsis, the Scythian philosopher. The anchors with two teeth were called ἀμφίβολοι or ἀμφίστομοι, and from ancient monuments appear to have been much the same with those used in our days, except that the stock is wanting in them all. Every ship had several anchors, the largest of which, corresponding to our sheet-anchor, was never used but in extreme danger, and was hence peculiarly termed ἱερά or sacra; whence the proverb sacram anchoram solvere, as flying to the last refuge.

Up to the commencement of the present century what was termed the "old plan long-shanked" anchor seems to have been generally used. It was made of wrought iron, but the appliances of the anchor smith were so crude that little dependence could be placed upon it. About this time public attention was drawn to the importance of the anchor by a clerk of Plymouth yard named Pering, who published a book, and argued, from the number of broken anchors which came to the yard for repair, that there "must be something wrong in the workmanship—undue proportion or the manner of combining the parts." Mr Pering altered the sectional form, made the arms curved instead of straight, used iron of better quality, and introduced improvements in the process of manufacture. Since 1820 about 130 patents have been taken out for anchors; and the attention thus given to the subject, with the introduction of steam hammers and furnaces, the substitution of the fan blast for the old bellows, and the better knowledge obtained of the forgeman's art, have rendered the anchor of the present day so far superior to that of fifty years ago, that we rarely hear at one being broken, the ground in which it is embedded generally giving way before the anchor.

Fig. 1.—Common Anchor. Fig. 2.—Admiralty's. Fig. 3.—Rodger's.

Fig. 1 represents the "common" anchor. The various parts are known by the following terms:—The shank is the straight part, ab; the square, ac, is that part of the shank to which the stock and the shackle are attached; d is the crown; de and df the arms; gg the palms or flukes; the pee, the bill, or the point is the extreme end of the arm beyond the palm; the blade is the part of the arm at the back of the palm; h is the shackle or ring to which the cable is attached; kl is the stock, placed at right angles to the plane of the arms and shank. The use of the stock is to "cant" the anchor. If it falls with the arms on the ground, the other end resting on the end of the stock, the pull of the cable will turn it over, so that the stack will lie upon the ground, and the weight of the crown and arms then resting upon the sharp point, will cause it to enter the soil and take fast hold.

1.— Chain and Anchor: for Steam Vessels required by Lloyd’s Register of British and Foreign Shipping (1874).

Minimum Weights of Anchors ex. Stock, Sizes and Length of Chain Cables, and the Proof Strain to which they are to be tested; also Sizes and Length of Hawsers and Warps,—the Anchors and the Links of the Chains to be of unexceptional form and proportions.

2.—Chains and Anchors for Sailing Vessels required by Lloyd’s Register of British and Foreign Shipping (1874).

¹ The rules for the building and classification of iron ships provide that "their equipment is to be regulated by the number produced by the sum of the measurements of the half moulded breadth of the vessel amidships, her depth from the upper part of keel to the top of the upper deck beams, and the girth of her half midship section to the same height, multiplied by the vessel's length, for a one, two, and three decked vessel, and for a spar-decked steam vessel."

² Two of the bower anchors must not be less than the weight set forth above; in the third a reduction of 15 per cent. will be allowed.

3.—Weights of Anchors and Sizes of Cables and Messengers for all classes of Screw Ships and Vessels of H.M. Navy. (The weight given for Anchors is exclusive of the Stock.)

Weight of Anchors supplied to Boats.—42 ft. Launch, 120 ℔; 32 ft. Pinnace, 56 ℔; 30 ft. Cutter, 40 ℔; Jollyboats or Gigs, 30 ℔.

The stock is made of iron in anchors of 60 cwt. and under, and of wood for anchors above that weight. A wooden stock (fig. 8) is made of English oak in two pieces; they are scored over the square so as to leave a space of about 2 in. clear between them at the shank and to touch at the extremities. It is made parallel for about ⁠1/6⁠th of its length at the centre, tapering from thence to the extremities, the side next the shackle being kept straight and the remaining three sides tapered. The section at any part is square, the dimensions being ⁠1/10⁠th of the length at the centre and half of this at the ends. The two pieces are fastened together by four iron bolts near the shank, six or eight treenails, au11 six iron hoops at the ends. The hoops are driven on tightly while hot, so that the contraction of the iron in cooling may draw the parts closely together. A projection, termed a nut, shown by the dotted lines at a,a, in fig. 8, is left on the square to prevent any lateral motion of the stock. An iron stock is made in one forging, so as to pass through a hole a, punched in the square. The stock has a shoulder b, which fits against the side of the shank when it is in the position for action as in fig. 1, and it is secured by a key driven tightly on the other side of the shank. The advantage of this is, that the stock can be unshipped and laid along the shank for convenience of stowing, as shown in fig. 4. The weight of the stock, whether of wood or iron, is about ⁠1/6⁠th that of the anchor.

Fig. 4.—Iron stock unshipped for stowing.

Fig. 4.—Iron stock unshipped for stowing.

The shank and each arm are forged under the steam-hammer in three pieces, and are then welded together at m and n, fig. 8. The welding is done by the "Hercules," which is a heavy iron ram placed over an anvil, so that it can be raised by steam power to a height of some 9 or 10 feet, and then let fall, being guided in its descent by three men, who hold rods attached to it. It is needless to say that the welding must be carefully done, as the whole strength of the anchor depends upon it.

To ensure safety, every anchor should be tested at a public testing house to ⁠1/3⁠d of its breaking strain. The anchor is held by a chain attached to the shackle, and the strain is applied to each arm separately at ⁠1/3⁠d of its length from the point. The proof of the anchor is that it must show no sign of fracture, and that if any deflection is caused by the strain, it must return very nearly to its original shape. A good anchor, after being deflected half an inch, will return to its former shape, leaving no permanent set.

The size of anchors for various ships has been determined by practice, but is based upon the theory that as the anchor is required to withstand the force brought upon the ship by the wind and tide, which would otherwise cause her to drift, its strength must be nearly proportional to her resistance. A result which will accord with sound practice may be obtained by calculating the resistance of a given ship at a speed or twelve knots, and taking this tor the working load of the anchor. The working load should be half the testing strain, and consequently ⁠1/6⁠th of the breaking strength.

A large ironclad carries 8 anchors,—2 bower, 2 sheet, 1 stream, 1 stern, end 2 kedge. The bower anchors (fig. 7) are stowed at the bow, and are for ordinary use in a roadstead; if there is any difference in weight, the heavier is stowed on the starboard side, and is termed the best bower. The sheet anchors (fig. 8) are stowed as far forward as is convenient in the waist of the ship, and are sometimes called the waist anchors; they are only used in cases of emergency, or in the event of any accident befalling the bowers. The stream anchor is for use in a river or sheltered place, where a small anchor is sufficient to hold the ship. The stern anchor is use when it is required to moor at both head and stern, as is the case when there is not room for the ship to swing with the tide. The kedge anchors are generally of different sizes, one large and one small; they are used to warp the ship along a narrow channel, the kedge being carried out in a boat with the hempen cable attached to it, and dropped; the ship can then still be hauled to the anchor. Kedge anchors are still supplied in the Royal Navy, but are very rarely used, the service for which they are intended being generally performed by the aid of a steam-tug vessel.

The tables on pp. 4 and 5 give the sizes and number of anchors and cables carried by ships of the Royal Navy, and those required by Lloyd's rules to be carried in merchant ships. The sheet and bower anchors are of the same size, and are given in the tables under the heading “Bower.”

Public attention having been directed to the subject of anchors by the specimens which were exhibited at the Exhibition of 1851, a committee was appointed by the Admiralty in the succeeding year to consider and report upon the qualifications of the various kinds. The committee determined the qualities it was desirable for an anchor to possess, and assigned numerical values to each. The following tables give the result of their labours, showing the number of marks obtained by each anchor under trial:—

Table showing the relative order in which the several Anchors stand with regard to each of the properties essential to a good Anchor—the names arranged alphabetically.

Table showing the estimated numerical values of the several Anchors in regard to the properties considered essential to a good Anchor.

Note.—This Table only professes to show approximate values, and has no pretensions to mathematical accuracy or precision.

The following is a recapitulation of the order in which the anchors were ranked by the committee, together with their relative percentage of inferiority or superiority in the Admiralty anchor, the value of which, as given in the foregoing table (18·17), was taken as the standard or unit:—

The decisions of the committee have been much questioned, one of the objections being that the qualities of strength and holding on, neither of which is of any use without the other, were assigned such different values as 15 and 80; it has also been stated that the Admiralty anchor was treated unfairly, as one was taken promiscuously out of store for the trial, whereas the other competing anchors were made specially for it.

The Admiralty anchor (fig. 2) differs only from the ordinary anchor in having a nut, a, worked on the square, so that a wooden stock may he fitted temporarily if the iron stock is damaged, and that its proportions and form have been carefully considered and definitely fixed. Lenox's and Aylen's were modifications of the Admiralty anchor. Mitcheson's was of a difficult section to forge, and consequently expensive, and was withdrawn from the test of strength. Isaac's was of a peculiar construction, and may be passed over as more curious than useful.

Rodger's anchor, placed second on the list, was one of Captain Rodger's, R.N., who for the last forty years has devoted considerable pains to the improvement of anchors. Among his earlier inventions is an anchor with a hollow shank, to obtain greater strength with a given weight of iron; then an anchor without a palm, which he termed a “pickaxe anchor;” afterwards a “small-palmed” anchor; and by a patent taken in 1863, an “indented small-palmed anchor” (figs. 3 and 7). The stock is of iron in large as well as small anchors, and is made with a mortice, to fit over the shank instead of passing through it. It is somewhat heavier than the stocks of other anchors; the arms are shorter than usual in proportion to the length of the shank, and are of a wedge shape, varying in sharpness from the throat to the head of the palms; the back part of the arms is parallel from palm to palm; the palm is double concave on the front, and has a small border at the edge for confining the soil through which it is dragged; it also has a large indentation on the back for the same purpose and to save weight; the shank is rectangular at its junction with the arms, and square close to the collar for the stock; the crown is made longer than usual, and has a large countersunk hole in its centre to save weight. 11 is claimed for this anchor that the peculiar form of the palms and arms, with the hole in the crown, give it great holding power, and that it will bury itself in the soil until the upper palm is beneath the surface, and consequently is not liable to be fouled by the cable.

Fig. 5.—Trotman's anchor.

Fig. 5.—Trotman's anchor.

Trotman's anchor (fig. 5), which obtained the highest place in the committee's estimation, was an improved Honiball's (Porter's). The stock is of iron, similar to the Admiralty anchor; the shank is of rectangular section, somewhat larger in the centre than at the ends, and is made fork-shaped at one end to receive the arms; the arms are in one piece, and are connected to the shank by a bolt passing through their centre. The peculiarity of the anchor is that the arms pivot about this bolt, so that when it takes hold the upper fluke is brought in contact with the shank, thus reducing the height above ground, and rendering it almost impossible for the cable to get entangled round it, or, in other words, for the anchor to become foul.

Of the anchors tested by the committee, Trotman's, Rodger's, and the Admiralty find the most favour at the present time. Trotman's and the Admiralty have undergone no alteration, but Captain Rodgers has taken out two patents for improvements in his anchor since the committee reported.

Fig. 6.—Martin's.

Fig. 6.—Martin's.

We now come to an anchor of entirely different shape from the preceding, patented by a Frenchman named Martin. The anchor is represented in fig. 6 in the position in which it lies on the ground just before taking hold. The shank is made in one forging, is of rectangular section having a shoulder for the stock to fit against, and is increased both in thickness and area at the crown; the arms with the palms are forged in one piece, and then bent to the required shape; one of the arms is passed through a hole in the crown and is kept in position by a bolt screwed through the end of the crown, so that its point reaches a little way into an indent made for it in the round part at the back of the arms. Until very recently this securing bolt was placed in the shank in a vertical position (supposing the anchor to be lying with the palms horizontal), so as to cut into the hollow part at the front of the bent arm. A very strong shoulder is worked on the arms, so as to fit in a groove on one side of the shank, in such a manner that the arms will revolve through an angle of 30° either way. The stock is fitted over the shank as shown, and secured by a key, which fixes it tightly against the shoulder left on the shank. The advantages of Martin's anchor are as follows—It is self-canting; it must fall in the position shown in the figure, and the weight of the arms, together with the pull of the cable, presses their sharp points into the soil, so that it takes hold immediately; it is impossible to foul it; it stows much more neatly than any other anchor; its holding power is very great, as both arms are in the soil at the same time, and the stock, which is flat and broad, adds materially to this quality; the strength is also very great. At an experiment made at Portsmouth dockyard in March 1867, two of the anchors were subjected to a strain of 50 per cent. over the Admiralty proof; the arms were deflected but three-tenths of an inch by this great strain, and when it was removed they regained their former shape. The anchor is made in three separate forgings without a weld. Unmasted turret ships, which have an all-round fire, are, almost without exception, fitted with Martin's anchor on account of the neatness with which it can be stowed, as the stock of any other anchor, if not unshipped, would obstruct the fire of the guns. The Admiralty allow a reduction of 25 per cent. in weight for Martin's anchor, using an 80 cwt. Martin where a 90 cwt. Admiralty or Rodger's anchor, weighing with its stock from 108 to 112 cwt., would be fitted, the weight given for Martin's anchor including the stock.

Smith's patent stockless anchor has been highly spoken of. It is a modification of Martin's anchor, but without the stock.

A bower anchor is stowed in H.M. service as shown in fig. 7. A, is the cathead; B, the fish davit; C, and E, bol- lards; D, the bill-board. The anchor is held in place by two chains, a and b, termed the cat-stopper and shank painter respectively, each of which is fitted with a long link at one end. A bolt b, about 5 or 6 inches long, is fixed on the side of the cathead, on a hinge at its lower end; it is held in the upright position by another bolt c, which passes through the cathead, and is worked by a lever d; d is provided with a hole at the end for a lanyard, so that two or three men can pull it. This whole arrangement is termed a slip-stopper. A somewhat similar combination of bolts and levers is fitted close to the bill-board D, e being a short bolt secured at its lower end with a hinge to the ship's side; and f a hooked lever which holds it in its upright position; f has a socket at its inboard end, to which a shifting arm, provided with a lanyard like the lever d, is fitted. The cat-stopper is rove through the shackle of the anchor, and the long link placed over the bolt b; it is then passed over a cleat g, on the side of the cathead, and belayed at the bollards C. The end of the shank painter is passed under the crown and over the shank; its long link is placed over the bolt e, and it is belayed at the bollards E. When it is desired to let go the anchor, the arm is shipped at f, and the lanyards at f and d are manned; then, at the word of command (given, if the ship is rolling, when she lurches towards the side on which the anchor is stowed), the men pull the lanyards, and b and e are released simultaneously, the links of the cat-stopper and shank painter drop off, and the anchor falls clear of the ship. In merchant ships it is not usual to fit the second slip-stopper, 6 and e; in this case it is necessary, before letting go, to "cock-bill" the anchor,—that is, to ease away the shank painter, so that the anchor hangs by the cathead alone. The next thing is to "weigh" the anchor. It is hove up by the capstan, and when it appears at the bows, the operations of "catting" and "fishing" have to be performed. A chain called the "cat pendant' is rove over the sheave in the cathead, and shackled to a short piece of a similar chain attached to the anchor at one end, and stoppered to the cable at the other; the inboard end of the cat pendant is taken to a leading block on the opposite side of the ship, and a purchase tackle attached to it, so as to give the men a run right aft. When all is ready, the word is given, and the men run away with the purchase until the anchor hangs from the cathead instead of the hawse-pipe; it is then said to be "catted." A chain rove through the block at the head of the fish davit, and having a large hook at the end, is then hooked to the inner arm of the anchor, which is then raised and swung inboard (the fish davit being made to revolve), so that the fluke rests upon the bill-board D, and the anchor is "fished." The cat-stopper and shank painter are then rove, and all made ready to let go again at a moment's notice.

Fig. 7.—Bower Anchor, and manner of stowing.

Fig. 7.—Bower Anchor, and manner of stowing.

The cathead shown in the figure is made of plates and angle irons, and is similar in shape to the old wooden cat- heads; it is fitted with a single sheave h, made to swivel so as to give a fair lead for the chain when the anchor is at the hawse-pipe. Catheads are frequently made of solid forgings, with a block hanging from the head for the cat pendant or fall. In ships designed for ramming, the cat-head is made to revolve like the fish davit B, so that it can be turned inboard, and there will be no projection on the bow to foul the enemy's rigging.

Fig. 8 shows a sheet anchor as stowed in a man-of-war. The anchor rests upon stout iron rods, a, a, called tumblers; they are connected to the ship's side at the lower ends, so that they will fall outwards. b, b, are short bolts to keep the anchor in its proper position, with the tumblers slightly inclining outboard. Both a, a, and b, b, are fitted to the shank of the anchor, and so arranged that rope lashings passing round the shank ean be secured to them. A strong bolt, fitted with three lugs, c, d, and e, is secured to the ship's side by eye-bolts, which allow it to revolve. Chains, f and g, fastened to the ship's side at one end, are passed round the shank of the anchor, and held by the lugs c and e at the other. A slip-stopper, h, clasps the lug d, and keeps the bolt in the position shown; the inner fluke of the anchor rests on the bill-board k, the point is held down by a securing chain fitted with a slip at 7, and the upper end of the stock is secured in a similar way. When it is desired to "let go," the rope lashings on a, a, and b, b, are cut, the slips at the point and stock are knocked away, and then the stopper h is the only thing which holds the anchor. A shifting lever, shown by dotted lines, is fitted to a socket in h; when a strain is brought upon this, the lug d is released from the grip of the stopper h, and the anchor let go, the tumblers, a, a, throwing it clear of the ship.

Fig. 8.—Stowing a Sheet Anchor.

Fig. 8.—Stowing a Sheet Anchor.

It should be observed that whenever a slip-stopper is fitted, care must be taken, by placing a pin at the back of it, or otherwise, to prevent the anchor being let go by accident.

Stern and stream anchors are stowed at the stern of the ship in the way described for sheet anchors.

The kedge anchors are generally stowed in the main-chains.

Sheet, stream, and stern anchors being very rarely used, have to be re-stowed by the aid of the yard-arm, without any special appliances being fitted.

Fig. 9.—Buoy Mooring Block.

Fig. 9.—Buoy Mooring Block.

Fig. 10.—Cast-iron Mooring Anchor.

Fig. 10.—Cast-iron Mooring Anchor.

Fig. 11.—Mushroom Anchor.

Fig. 11.—Mushroom Anchor.

Mooring anchors are those which are placed in harbours, &c., for the convenience of vessels frequenting them. A large buoy is attached to the end of the mooring cable, and the ship is made fast to a ring-bolt fitted on the buoy. Mooring anchors are not limited by considerations of weight, &c., as other anchors are, the only requirements being that they have sufficient holding power, and do not project above the ground, as any projection in the shallow waters in which they are usually placed would render ships liable to injury from grounding on them, and be dangerous to fishing-nets, &c. Mooring anchors may there- fore be of stone, as shown in fig. 9; or of cast-iron, as in fig. 10. Mushroom anchors (fig. 11), first proposed for ships, are now only used for moorings. An old anchor which has one arm dam- aged is frequently used as a mooring anchor, the damaged arm being bent down close to the shank; the anchor is sunk with the bent arm uppermost, and there is no projection above the ground. In harbours where there is not much room it is usual to place two anchors, connected by a cable, in a line at right angles to the direction of the tide; a swivel is fitted at the centre of this cable, and the buoy chain is made fast to the swivel. With this arrangement the ship does not sweep such a large circle in swinging.

Fig. 12.—Mooring Anchor.

Fig. 12.—Mooring Anchor.

The best mooring anchor which has yet been devised is shown in fig. 12. Its shank is a round bar of wrought iron, a, about 7 feet in length and 6 inches in diameter; it is increased at 6 to 9 inches diameter for about 1 foot of its length, and terminated at f similarly to the point of a gimlet; holes are made in the stout part b, and a screw flange of 3 feet diameter is cast around it; the molten metal gets into the holes and makes a good connection with the wrought-iron shank. A swivel c, to which a large shackle d, is attached, is fitted on as shown, and secured by a strong nut; the end of the shank e is made square. To place this anchor in about 8 fathoms of water, four iron bars, each about 17 feet in length, and provided with a socket at one end and a square head at the other, are used. As the anchor is lowered the socket of the first bar is fitted on at e, and the socket of the second bar in its turn fitted to the square end of the first, and so on till the anchor reaches the bottom. A drumhead, similar to a capstan, is then fitted on the last bar, and capstan bars shipped in it; by these means the anchor is turned round, and so screwed into the ground. It must be sunk through the soft mud or sand into the harder soil beneath it, and when this is done the holding power of the anchor is enormous. An anchor of the dimensions given weighs about 14 cwt., and will hold far more than a cast-iron mooring anchor of 7 tons. The only objections to it seem to be the difficulty of removing it if the moorings are required to be taken up, and that special appliances are required for putting it down.

A good anchorage is where there are from 10 to 20 fathoms of water, and the ground is not rocky or loose sand. Where there are more than about 20 fathoms the cable bears too nearly perpendicular, and is liable to trip the anchor. For anchoring in ordinary weather the length of cable veered out is about three times the depth of water.

(t. m.)